JP2007246578A - Blowing agent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a blowing agent improving the foaming magnitude by leaps and bounds by using a specific microcapsules and chemical blowing agent excellent in high foaming property, and a foamable polymer composition containing the blowing agent. <P>SOLUTION: This blowing agent consisting of (A) microcapsules having 1 to 1,000 μm mean particle diameter and containing a low boiling liquid and (B) a chemical blowing agent is provided by showing 100 to 200°C blowing start temperature of the (A) and (B), and 150 to 250°C maximum blowing temperature of the blowing agent. The blowing agent can be used as a foamable polymer composition by being blended with a thermoplastic cross-linkable rubber composition consisting of (C-1) a cross-linkable rubbery polymer and (C-2) a thermoplastic resin. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a foaming agent. More specifically, the present invention relates to a foaming agent having excellent high foamability.

Conventionally, foam has been widely used as home appliance parts, automobile exterior parts, housing / building material parts, and the like. However, physical foaming agents such as air, carbon dioxide, nitrogen gas, fluorinated hydrocarbons, chlorinated hydrocarbons, and aliphatic hydrocarbons are generally used to produce foams with a high expansion ratio. For this reason, a large-scale manufacturing apparatus in consideration of safety is required, and there are economic or technical restrictions.
On the other hand, a microcapsule containing a chemical foaming agent and a low-boiling liquid is known as a foaming agent other than a physical foaming agent. For example, a thermally expandable resin composition of a microcapsule (see Patent Documents 1 and 2) is disclosed. Has been. However, since it is difficult to obtain a foam having a high expansion ratio with the above foaming agent, a foaming agent that can withstand practical use is demanded.

Japanese Examined Patent Publication No. 58-042212 Japanese Patent Publication No.58-042209

  In view of such a current situation, an object of the present invention is to provide a foaming agent that does not have the above-described problems, that is, has high foamability.

As a result of intensive investigation of highly foaming foaming agents, the present inventors have surprisingly found that by using specific microcapsules and chemical foaming agents, the foaming ratio can be dramatically improved, and the present invention has been completed. did.
That is, this invention is a foaming agent as described below, and a foaming polymer composition containing this foaming agent.

(1) In a foaming agent comprising a microcapsule (A) having an average particle diameter of 1 to 1000 μm and a chemical foaming agent (B) encapsulating a low boiling point liquid, the microcapsule (A) and the chemical foaming agent (B The foaming agent is characterized by having a foaming start temperature of 100 to 200 ° C and a maximum foaming temperature of 150 to 250 ° C.
(2) A foamable polymer composition comprising the foaming agent according to (1) and a polymer (C).
(3) The above characterized in that the polymer (C) is a crosslinked thermoplastic crosslinked rubber composition comprising a crosslinkable rubber-like polymer (C-1) and a thermoplastic resin (C-2) ( 2. The foamable polymer composition as described in 2).
(4) An ethylene / α-olefin copolymer (C-1) produced using a metallocene catalyst, wherein the crosslinkable rubber-like polymer (C-1) contains ethylene and an α-olefin having 3 to 20 carbon atoms. -1), or a hydrogenated rubber in which 50% or more of all olefinic double bonds of the unsaturated rubber composed of a homopolymer and / or copolymer having a double bond in the main chain and side chain are hydrogenated ( The foamable polymer composition as described in (3) above, which is one or more crosslinkable rubber-like polymers selected from C-1-2).
(5) The foamable polymer composition as described in (3) or (4) above, wherein the thermoplastic resin (C-2) is an olefin resin.
(6) The expandable polymer composition as described in any one of (3) to (5) above, which is crosslinked with a crosslinking agent (D).
(7) The above (2), further comprising at least one additive (E) selected from the group consisting of a softener, a powdery compound that does not melt at 250 ° C., a styrene thermoplastic elastomer, and a resin wax. The foamable polymer composition according to any one of to (6).
(8) A foam obtained by molding the foamable polymer composition according to any one of (2) to (7) above by an injection molding method, an extrusion molding method or a blow molding method.

  The foaming agent of the present invention is excellent in high foamability.

The present invention will be specifically described below.
The foaming agent of the present invention comprises a specific microcapsule (A) and a specific chemical foaming agent (B).
Here, it is important to use (A) and (B) together. In (A), the lower the melt viscosity, the lower the resistance during foaming, and thus the expansion ratio is increased. On the other hand, in (B), the higher the melt tension, the higher the expansion ratio. For this reason, the foaming ratio exceeding the additivity can be achieved by using the polymer melting behavior in contradiction with each other.
And when the foaming start temperature of (A) and (B) is 100 ° C. to 200 ° C. and the maximum foaming temperature is 150 to 250 ° C., it was found that the foaming ratio is remarkably improved, and the present invention was completed. .
Hereinafter, each component of the present invention will be described in detail.

<Microcapsule (A)>
In the present invention, the microcapsule (A) is a microcapsule containing a low boiling point liquid and having an average particle diameter of 1 to 1000 μm, preferably 1 to 100 μm, most preferably 1 to 50 μm, and a foaming start temperature of 100 ° C. to If it is 200 degreeC, Preferably it is 150 degreeC-200 degreeC and a maximum foaming temperature is 150-250 degreeC, Preferably it is 200-250 degreeC, It will not restrict | limit in particular. In such a microcapsule, the base material of the outer shell is softened, the encapsulated low boiling point liquid is gasified, and expands like a balloon with a true sphere and no internal pressure.

The low boiling point liquid is conventionally referred to as a physical blowing agent, and examples thereof include low molecular weight hydrocarbons such as propane, butane, isobutane, pentane, neopentane, hexane, isohexane, and heptane, and halides of methane and ethane.
The microcapsule is a hollow body of an inorganic compound and / or an organic polymer, and its base material is an inorganic compound such as glass, silica, shirasu, carbon, alumina, zirconia, or a phenolic resin, a vinylidene chloride resin, an acrylonitrile system. Organic polymers such as resins.
(A) in the present invention is preferably a microcapsule based on an organic polymer, which is produced by a known emulsion polymerization method or suspension polymerization method, and is disclosed in, for example, Patent Documents 1 and 2 above.

<Chemical foaming agent (B)>
The chemical foaming agent (B) is a component for generating a gas such as nitrogen gas or carbon dioxide gas by heating to the decomposition temperature, the foaming start temperature is 100 ° C to 200 ° C, and the maximum foaming temperature is 150 to There is no particular limitation as long as the requirement of 250 ° C. is satisfied.
Such chemical blowing agents are classified into organic and inorganic chemical blowing agents. Further, organic chemical foaming agents are classified into thermal decomposition types such as azo compounds, nitroso compounds, hydrazine derivatives, semicarbazide compounds, azide compounds, triazole compounds, etc., and reaction types of isocyanate compounds. The inorganic chemical foaming agent is divided into a thermal decomposition type such as bicarbonate / carbonate, nitrite / hydrogen compound, and a reaction type such as sodium bicarbonate + acid, hydrogen peroxide + yeast bacteria, zinc powder + acid. Divided. Of these, inorganic chemical foaming agents are preferable to organic ones, and thermal decomposition type inorganic chemical foaming agents are more preferable.

<Polymer (C)>
In the present invention, the polymer (C) in which (A) and (B) can be blended is a thermoplastic polymer or a thermosetting polymer, but a thermoplastic polymer is preferred. The thermoplastic polymer is classified into a thermoplastic resin and a thermoplastic rubbery polymer (elastomer), and is not particularly limited.
The thermoplastic resin is, for example, a polystyrene type, a polyphenylene ether type, a polyolefin type, a polyvinyl chloride type, a polyamide type, a polyester type, a polyphenylene sulfide type, a polycarbonate type, or a polymethacrylate type, or a mixture of two or more. Can be used. In particular, an olefin resin is preferable as the thermoplastic resin.

  The thermoplastic rubber-like polymer preferably has a glass transition temperature (Tg) of −10 ° C. or lower. Examples of such a rubber-like polymer include polybutadiene, poly (styrene-butadiene), and poly (acrylonitrile). -Butadiene) and other diene rubbers, saturated rubbers obtained by hydrogenation of the above diene rubbers, isoprene rubbers, chloroprene rubbers, acrylic rubbers such as polybutyl acrylate, ethylene-propylene copolymer rubbers, ethylene-propylene-diene monomer ternary Examples thereof include crosslinked rubber or non-crosslinked rubber such as copolymer rubber (EPDM) and ethylene-octene copolymer rubber, and thermoplastic elastomer containing the rubber component.

Among (C), a crosslinked thermoplastic polymer composed of a crosslinkable rubber-like polymer (C-1) and a thermoplastic resin (C-2) is more preferable.
In the present invention, a preferred crosslinked rubber polymer (C-1) of a thermoplastic polymer is, for example, the above-mentioned thermoplastic rubber polymer, and Mooney measured at 100 ° C. of (C-1). The viscosity (ML) (based on ISO 289-1985 (E)) is preferably 20 to 150, more preferably 50 to 120.

  In the present invention, one of the preferred polymers among the crosslinkable rubber-like polymer (C-1) is an ethylene / α-olefin copolymer, which is a copolymer of ethylene and an α-olefin having 3 to 20 carbon atoms. More preferred are polymers. Examples of the α-olefin include propylene, butene-1, pentene-1, hexene-1, 4-methylpentene-1, heptene-1, octene-1, nonene-1, decene-1, undecene-1, dodecene- 1 etc. are mentioned. Among them, hexene-1, 4-methylpentene-1, and octene-1 are preferable, and an α-olefin having 3 to 12 carbon atoms is particularly preferable, and propylene, butene-1, and octene-1 are most preferable.

  Further, the crosslinkable rubbery polymer (C-1) can contain a monomer having an unsaturated bond, if necessary, for example, conjugated diolefins such as butadiene and isoprene, and 1,4-hexadiene. Non-conjugated diolefins such as dicyclopentadiene, cyclic diene compounds such as norbornene derivatives, and acetylenes. In particular, ethylidene norbornene (ENB) and dicyclopentadiene (DCP) are most preferable.

In the present invention, an ethylene / α-olefin copolymer (hereinafter referred to as an ethylene / α-olefin copolymer of (C-1)) which is one of the preferred copolymers of (C-1) is known. It is preferable to produce using a metallocene catalyst.
In general, a metallocene catalyst comprises a cyclopentadienyl derivative of a group IV metal such as titanium or zirconium and a co-catalyst, and is not only highly active as a polymerization catalyst but also a polymer obtained in comparison with a Ziegler catalyst. The molecular weight distribution is narrow and the distribution of the α-olefin having 3 to 20 carbon atoms, which is a comonomer in the copolymer, is uniform.

The ethylene / α-olefin copolymer (C-1) used in the present invention preferably has an α-olefin copolymerization ratio of 1 to 60% by weight, more preferably 10 to 50% by weight, most preferably Preferably it is 20 to 45 weight%. The copolymerization ratio of α-olefin is preferably 60% by weight or less from the viewpoints of the hardness and tensile strength of the composition, and is preferably 1% by weight or more from the viewpoints of flexibility and mechanical strength.
The density of the (C-1) ethylene / α-olefin copolymer is preferably in the range of 0.8 to 0.9 g / cm ³ . By using an ethylene / α-olefin copolymer having a density in this range, the thermoplastic elastomer composition of the present invention having excellent flexibility and low hardness can be obtained.

  The ethylene / α-olefin copolymer (C-1) used in the present invention preferably has long chain branching. Due to the presence of long chain branching, it is possible to make the density smaller compared to the proportion (% by weight) of the α-olefin copolymerized without reducing the mechanical strength. An ethylene / α-olefin copolymer having high hardness and high strength can be obtained. The ethylene / α-olefin copolymer having a long chain branch is described in US Pat. No. 5,278,272.

The ethylene / α-olefin copolymer (C-1) preferably has a melting point peak of a thermobalance (DSC) above room temperature. When it has a melting point peak, the form is stable in the temperature range below the melting point, it is easy to handle and has little stickiness.
The melt index of the ethylene / α-olefin copolymer (C-1) used in the present invention is 0.01 to 100 g / 10 min (190 ° C., 2.16 kg load (0.212 Pa)). The thing of the range is used preferably, More preferably, it is 0.2-10 g / 10min. From the viewpoint of crosslinkability of the thermoplastic crosslinked rubber composition of the present invention, 100 g / 10 min or less is preferable, and from the viewpoint of fluidity and processability, 0.01 g / 10 min or more is preferable.

  In the present invention, the hydrogenated rubber (C-1-2), which is another preferred copolymer of (C-1), is a homopolymer rubber of at least one conjugated diene monomer, or a conjugated diene. A copolymer rubber comprising a monomer and an aromatic vinyl monomer, preferably a hydrogenated copolymer rubber having a random copolymer full hydrogen bond hydrogenation rate of 50% or more, Particularly, a hydrogenated copolymer rubber in which 50% or more of all olefinic double bonds of an unsaturated polymer rubber comprising a polymer and / or copolymer having a double bond in the main chain and side chain are hydrogenated. Preferably there is.

  In the hydrogenated copolymer rubber, if necessary, for example, olefinic, methacrylic ester, acrylic ester, unsaturated nitrile, vinyl chloride monomer and other conjugated dienes can be copolymerized. A monomer (hereinafter referred to as a copolymerizable monomer) can be copolymerized.

  Examples of the conjugated diene monomer include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3- Hexadiene, 4,5-diethyl-1,3-octadiene, 3-butyl-1,3-octadiene, chloroprene and the like can be mentioned, and 1,3-butadiene, isoprene and 1,3-pentadiene are preferable, Most preferred are 3-butadiene and isoprene.

  Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, p-methylstyrene, t-butylstyrene, divinylbenzene, N, N-dimethyl-p-aminoethylstyrene, and vinylpyridine. Styrene and α-methylstyrene are preferable. The aromatic monomers can be used alone or in combination of two or more. The aromatic vinyl monomer content is preferably 0 to 80% by weight, more preferably 0 to 50% by weight, and most preferably 0 to 30% by weight.

  In the hydrogenated rubber as (C-1), the vinyl bond in the conjugated diene monomer portion before hydrogenation may be present uniformly in the molecule, or may increase or decrease or decrease along the molecular chain. In addition, a plurality of blocks having different vinyl bond contents may be included. When the aromatic vinyl monomer and / or copolymerizable monomer is included, the conjugated diene monomer and the aromatic vinyl monomer and / or copolymerizable monomer are randomly bonded. However, it may contain a block-like aromatic vinyl monomer and / or a block-like copolymerizable monomer. The content of the block-like aromatic vinyl polymer is preferably 20% by weight or less, more preferably 10% by weight or less, based on the total aromatic vinyl monomer.

  The total olefinic double bonds in the hydrogenated rubber are 50% or more, preferably 90% or more, more preferably 95% or more, and the main chain has a residual double bond of 5% or less, and a side chain. The remaining double bond is 5% or less. Specific examples of such hydrogenated rubber include rubber-like heavys obtained by partially or completely hydrogenating diene rubbers such as polybutadiene, poly (styrene-butadiene), poly (acrylonitrile-butadiene), polyisoprene, polychloroprene. In particular, hydrogenated butadiene-based or hydrogenated isoprene-based rubber is preferable.

  Such a hydrogenated copolymer rubber can be obtained by partially hydrogenating the above-described diene rubber by a known hydrogenation method. For example, a method of hydrogenation using a triisobutylborane catalyst described in FLRamp, etal, J. Amer. Chem. Soc., 83, 4672 (1961), Hung Yu Chen, J. Polym. Sci. Polym. Letter Ed , 15,271 (1977), or hydrogenation using a toluenesulfonyl hydrazide or an organic cobalt-organic aluminum catalyst or an organic nickel-organic aluminum catalyst described in Japanese Patent Publication No. 42-8704 And the like.

  Here, particularly preferred hydrogenation methods are disclosed in JP-A-59-133203 and JP-A-60-220147 using inert catalysts that can be hydrogenated under mild conditions of low temperature and low pressure, or inert organic compounds. Contacting with hydrogen in a solvent in the presence of a catalyst comprising a bis (cyclopentadienyl) titanium compound and a hydrocarbon compound having a sodium atom, a potassium atom, a rubidium atom or a cesium atom This is the method shown in the gazette.

The hydrogenated copolymer rubber preferably has a 5 wt% styrene solution viscosity (5% SV) at 25 ° C. in the range of 20 to 300 centipoise (cps). A particularly preferred range is 25 to 150 cps.
The hydrogenated copolymer rubber preferably has crystallinity, and the endothermic peak calorific value, which is an index of crystallinity, is controlled by adding a polar compound such as tetrahydrofuran or controlling the polymerization temperature. The reduction of the endothermic peak heat amount is achieved by increasing the polar compound during the production of the rubbery polymer or increasing the 1,2-vinyl bond by decreasing the polymerization temperature.

The crosslinkable rubbery polymer (C-1) used in the present invention may be used by mixing a plurality of types. In such a case, the workability can be further improved.
In the present invention, the proportion of the polymer having a polystyrene equivalent molecular weight of 150,000 or less in the crosslinkable rubber-like polymer (C-1) is preferably 30% by weight or less, more preferably 25% or less, and further It is preferably 20% or less, most preferably 15% or less, and most preferably 10% or less. When the ratio is 30% or less, the crosslinkability is remarkably increased, and the mechanical strength, appearance, feel, wear resistance and oil resistance are improved.

  In the present invention, as a method for controlling the proportion of the polymer having a polystyrene-reduced molecular weight of 150,000 or less in the crosslinkable rubber-like polymer (C-1), the portion having a molecular weight of 150,000 or less is 30% or less. Examples thereof include a method for increasing the total molecular weight, a method for removing a portion having a molecular weight of 150,000 or less by an operation such as extraction, or a polymerization method in which a molecular weight of 150,000 or less is not selectively generated by a polymerization catalyst or the like.

  In the present invention, the thermoplastic resin (C-2) constituting the preferred crosslinked thermoplastic polymer is the above-mentioned thermoplastic resin, and is not particularly limited as long as it is dispersed with (C-1). Resin is preferable, and it is a copolymer containing ethylene or / and α-olefin having 2 to 20 carbon atoms such as ethylene or propylene resin, and propylene resin is particularly preferable.

Specific examples of propylene resins most preferably used among olefin resins include homopolypropylene, propylene and other α-olefins such as ethylene, butene-1, pentene-1, and hexene-1. A copolymer etc. are mentioned.
Specific examples of the propylene-based resin most preferably used in the present invention include homoisotactic polypropylene, propylene, and other α-olefins such as ethylene, butene-1, pentene-1, and hexene-1. Examples include isotactic copolymer resins (including blocks and random).

  In the present invention, among the components (C-2), (a) a propylene random copolymer resin such as a random copolymer resin of ethylene and propylene, which is a cross-linked olefin resin, or (a) and (b) A combination with a propylene block copolymer resin or a homopolypropylene resin, which is a decomposable olefin resin, is preferred. The appearance and mechanical strength are further improved by combining two types of olefin resins, such as a crosslinked olefin resin and a decomposable olefin resin.

Examples of the component (a) include a random copolymer resin of ethylene and propylene. When the ethylene component is present in the polymer main chain, it becomes a crosslinking point of the crosslinking reaction, and the characteristics of the crosslinked olefin resin. Indicates.
The component (b) is mainly composed of an α-olefin and preferably does not contain an ethylene unit in the polymer main chain. However, when an ethylene-α olefin copolymer is present as a dispersed phase, such as a propylene block copolymer resin, the characteristics of the decomposable olefin resin are exhibited.

  (C-2) may be a combination of a plurality of components (a) and (b). (A) Random copolymer resin with α-olefin mainly composed of propylene among components can be produced by a high pressure method, a slurry method, a gas phase method, a bulk method, a solution method, etc. Ziegler-Natta catalyst, single site, metallocene catalyst are preferred. In particular, when a narrow composition distribution and molecular weight distribution are required, a random copolymerization method using a metallocene catalyst is preferable.

  A specific method for producing a random copolymer resin is disclosed in European Patent Application No. 969043 or US Pat. No. 5,1984,401, and after introducing propylene into a reactor equipped with a stirrer, the catalyst is discharged from a nozzle. Add to gas phase or liquid phase. Next, ethylene gas or α-olefin is introduced into the gas phase or liquid phase of the reactor, and the reaction temperature and reaction pressure are controlled to conditions under which propylene is refluxed. The polymerization rate is controlled by the catalyst concentration and the reaction temperature, and the copolymer composition is controlled by the amount of ethylene or α-olefin added.

  The melt index of the olefin resin suitably used in the present invention is 0.1 or more from the viewpoint of fluidity and molding processability, and 100 g / 10 min (230 from the viewpoint of heat resistance and mechanical strength of the composition. Those having a range of not higher than 2.degree. C. and a load of 2.16 kg (0.212 Pa)) are preferably used.

In the present invention, (C-1) in 100 parts by weight of the rubber composition comprising (C-1) and (C-2) is 1% by weight or more from the viewpoint of mechanical strength and flexibility of the composition. From the viewpoint of the thermoplasticity, it is preferably 99% by weight or less, more preferably 10 to 90% by weight, and most preferably 20 to 80% by weight.
In the present invention, the composition comprising (C-1) and (C-2) may be one obtained by melt-mixing separate (C-1) and (C-2) with an extruder, Moreover, the polymerization type olefin type composition manufactured by superposing | polymerizing (C-1) and (C-2) may be sufficient. Such a polymerization-type olefin composition is a thermoplastic elastomer produced by a polymerization method comprising a dispersed phase of olefin rubber and a continuous phase of olefin resin. Usually, it is produced by a multistage polymerization method.

  In the present invention, the multistage polymerization method means a polymerization method in which a plurality of types of polymers can be continuously produced by performing multistage polymerization of two or more stages, instead of completing the polymerization once. However, this method is different from the usual polymer blending method in which a mixed resin composed of different kinds of polymers is obtained using a mechanical method.

  The olefinic crosslinkable rubber composition obtained by the multistage polymerization method is a copolymer obtained by multistage polymerization of (1) hard segment and (2) soft segment in a reactor. (1) The hard segment is typically a propylene homopolymer block or a copolymer block of propylene and an α-olefin, such as propylene / ethylene, propylene / 1-butene, propylene / ethylene / 1- Examples include binary or ternary copolymer blocks such as butene. The (2) soft segment is typically an ethylene homopolymer block and a copolymer block of ethylene and α-olefin, such as ethylene / propylene, ethylene / 1-butene, ethylene / propylene / 1-butene. Binary or ternary copolymer blocks such as

<Crosslinking agent (D)>
The thermoplastic crosslinked rubber composition in the present invention is preferably crosslinked with a crosslinking agent (D).
The crosslinking agent (D) contains the crosslinking initiator (D-1) as an essential component, and contains a polyfunctional monomer (D-2) and a monofunctional monomer (D-3) as necessary. The crosslinking agent (D) is used in an amount of 0.001 to 10 parts by weight, preferably 0.005 to 3 parts by weight, based on 100 parts by weight of the total of (A) and (B). Within the above range, the level of cross-linking is increased and the wear resistance of the composition is improved.

  Here, examples of the crosslinking initiator (D-1) include radical initiators such as organic peroxides and organic azo compounds, and specific examples thereof include 1,1-bis (t-butylperoxy). ) -3,3,5-trimethylcyclohexane, 1,1-bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-hexylperoxy) cyclohexane, 1,1 -Bis (t-butylperoxy) cyclododecane, 1,1-bis (t-butylperoxy) cyclohexane, 2,2-bis (t-butylperoxy) octane, n-butyl-4,4-bis ( peroxyketals such as t-butylperoxy) butane and n-butyl-4,4-bis (t-butylperoxy) valerate; di-t-butyl peroxide, dicumyl peroxide , T-butylcumyl peroxide, α, α′-bis (t-butylperoxy-m-isopropyl) benzene, α, α′-bis (t-butylperoxy) diisopropylbenzene, 2,5-dimethyl- Dialkyl peroxides such as 2,5-bis (t-butylperoxy) hexane and 2,5-dimethyl-2,5-bis (t-butylperoxy) hexyne-3; acetyl peroxide, isobutyryl peroxide , Octanoyl peroxide, decanoyl peroxide, lauroyl peroxide, 3,5,5-trimethylhexanoyl peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, and m-trioyl peroxide Oxides; t-butyl peroxyacete , T-butyl peroxyisobutyrate, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxylaurate, t-butyl peroxybenzoate, di-t-butyl peroxyisophthalate, Peroxyesters such as 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t-butylperoxymaleic acid, t-butylperoxyisopropyl carbonate, and cumylperoxyoctate; and t -Hydroperoxides such as butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide and 1,1,3,3-tetramethylbutyl peroxide List oxides Can.

  Among these compounds, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, di-t-butyl peroxide, dicumyl peroxide, 2,5-dimethyl-2, 5-bis (t-butylperoxy) hexane and 2,5-dimethyl-2,5-bis (t-butylperoxy) hexyne-3 are preferred.

  The (D-1) is preferably used in an amount of 1 to 80% by weight, more preferably 10 to 50% by weight in the component (D). 1% by weight or more is preferable from the viewpoint of crosslinkability, and 80% by weight or less is preferable from the viewpoint of mechanical strength.

In the present invention, the polyfunctional monomer (D-2) contained in the crosslinking agent (D) as necessary is preferably a radical polymerizable functional group as the functional group, and particularly preferably a vinyl group. Although the number of functional groups is 2 or more, it is effective particularly in the case of having 3 or more functional groups in combination with (D-3). Specific examples include divinylbenzene, triallyl isocyanurate, triallyl cyanurate, diacetone diacrylamide, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, ethylene glycol dimethacrylate, Triethylene glycol dimethacrylate, diethylene glycol dimethacrylate, diisopropenylbenzene, P-quinonedioxime, P, P'-dibenzoylquinonedioxime, phenylmaleimide, allyl methacrylate, N, N'-m-phenylenebismaleimide, diallyl Phthalate, tetraallyloxyethane, 1,2-polybutadiene and the like are preferably used. Triaryl isocyanurate is particularly preferable. These polyfunctional monomers may be used in combination.
(D-2) is preferably used in an amount of 1 to 80% by weight, more preferably 10 to 50% by weight in the crosslinking agent (D). 1% by weight or more is preferable from the viewpoint of crosslinkability, and 80% by weight or less is preferable from the viewpoint of mechanical strength.

The (D-3) used in the present invention is a vinyl monomer, preferably a radical polymerizable vinyl monomer, and an unsaturated nitrile such as an aromatic vinyl monomer, acrylonitrile, or methacrylonitrile. Monomers, ester monomers such as acrylic acid ester monomers and methacrylic acid ester monomers, unsaturated carboxylic acid monomers such as acrylic acid monomers and methacrylic acid monomers, maleic anhydride Examples thereof include unsaturated carboxylic acid anhydrides such as monomers, low molecular weight monomers such as N-substituted maleimide monomers, and macromonomers in which a vinyl group such as a methacryloyl group is substituted at one end of the polymer. it can.
The (D-3) is preferably used in an amount of 1 to 80% by weight, more preferably 10 to 50% by weight in the component (D). 1% by weight or more is preferable from the viewpoint of crosslinkability, and 80% by weight is preferable from the viewpoint of mechanical strength.

  In the present invention, the most preferable combination of the crosslinking agent (D) is 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane (trade name: Perhexa 25B, manufactured by NOF Corporation as a crosslinking initiator. ) Or Nippon Oil & Fats Co., Ltd., 2,5-dimethyl-2,5-bis (t-butylperoxy) hexyne-3 and polyfunctional monomer, manufactured by Nippon Kasei Co., Ltd., triallyl isocyanurate (TAIC) Is excellent in the mechanical strength and the retention of the softener when the softener described below is present.

<Additive (E)>
In the present invention, if necessary, at least one additive (E) selected from a softening agent, a powdery compound that does not melt at 250 ° C., a styrene thermoplastic elastomer, and a resin wax can be added.
The softener is preferably a process oil composed of paraffinic, naphthenic, aromatic hydrocarbons. In particular, naphthenic hydrocarbon-based process oils are preferred from the viewpoint of compatibility with paraffinic hydrocarbons or rubber. From the viewpoint of heat and light stability, the aromatic hydrocarbon content in the process oil is preferably 10% or less, more preferably 5% or less, in terms of the carbon number ratio of ASTM D2140-97. Most preferably, it is 1% or less.
These softeners are used in an amount of 5 to 500 parts by weight, preferably 10 to 150 parts by weight, based on 100 parts by weight of (C). Within the above range, the balance of dispersibility, flexibility and bleed resistance is excellent.

In the present invention, when abrasion resistance is required, polyorganosiloxane (F) can be added as necessary, and the kinematic viscosity at 25 ° C. of JIS-K2410 is 5000 centistokes (5 The polyorganosiloxane which is more than x10 < ^-3 > m < ² > / sec) is preferable.
The polyorganosiloxane is in the form of a viscous syrupy to gum, and is not particularly limited as long as it is a polymer containing an alkyl, vinyl and / or aryl group-substituted siloxane unit. Of these, polydimethylsiloxane is most preferred.

The kinematic viscosity (25 ° C.) of the polyorganosiloxane used in the present invention is 5000 CS (5 × 10 ⁻³ m ² / sec) or more, more preferably 10,000 CS (1 × 10 ⁻² m ² / sec). ) 10,000,000 ⁽¹⁰ m 2 / sec) below, and most preferably less than 50,000 CS (0.05m ² / sec) over 2 million ^(2m 2 / sec).

In the present invention, the amount of (F) added is preferably 0.001 to 20 parts by weight, more preferably 0.1 to 10 parts by weight, and most preferably 0 to 100 parts by weight of (C). .5 to 5 parts by weight.
In the present invention, other inorganic fillers, plasticizers, organic / inorganic pigments, heat stabilizers, antioxidants, ultraviolet absorbers, light stabilizers, flame retardants, silicone oils, foaming agents to the extent that they do not impair their characteristics It is possible to contain an antistatic agent and an antibacterial agent.

In the present invention, a general method such as a Banbury mixer, a kneader, a single-screw extruder, or a twin-screw extruder used for manufacturing a normal resin composition or an elastomer composition is employed for the production of the polymer composition. It is possible. In particular, a twin screw extruder is preferably used in order to achieve dynamic crosslinking efficiently. The twin-screw extruder disperses (C-1) and (C-2) uniformly and finely, and further adds other components to cause a crosslinking reaction. More suitable for manufacturing.
The thermoplastic crosslinked rubber composition in the present invention may be obtained by first melt-blending (C-1) and (C-2), then adding (D) and melt-mixing, or (C-1) (C-2) (D) may be added at the same time and melt-mixed, but a method in which (C-1) and (C-2) are uniformly melt-mixed and then crosslinked by (D) is preferred.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, this invention is not limited to these. In these examples and comparative examples, the test methods used for evaluating various physical properties are as follows.

1. Foam start temperature, maximum foam temperature
Using TMA100 and SSC5000 manufactured by Seiko Denshi Kogyo Co., Ltd., the coefficient of expansion was obtained from the expansion rate when the temperature was raised at a rate of temperature rise of 5 ° C./min.
2. Based polymer containing no foaming ratio (A) and (B) a density of (C) was measured according to JIS K6758, and _{d 0.} On the other hand, the foaming agent ((A), (B) ) was measured in the same manner the density of the foam composition comprising (C), and the _{d 1.} The expansion ratio is defined by the ratio d ₀ / d ₁ .

The following were used for each component used in Examples and Comparative Examples.
(A) Microcapsule A microcapsule having an average particle size of 20 μm was produced by the method described in Patent Documents 1 and 2 using heptane and polyacrylonitrile as the low boiling point liquid and the base material, respectively. (Referred to as MC)
(B) Chemical foaming agent Commercially available chemical foaming agents composed mainly of sodium hydrogen carbonate and citric acid and having different foaming start temperatures and maximum foaming temperatures were used. (Referred to as CB)

(C) Polymer (C-1) Crosslinkable rubbery polymer (C-1-1) Ethylene / α-olefin copolymer
a) Ethylene / propylene / ethylidene norbornene (ENB) copolymer (TPE-1)
It is produced by a method using a metallocene catalyst described in JP-A-3-163088. The composition ratio of ethylene / propylene / ENB of the copolymer is 72/24/4 (weight ratio), and the Mooney viscosity is 100. (Referred to as TPE-1)
b) Ethylene / propylene / ethylidenenorbornene (ENB) copolymer (TPE-2)
It is produced by a method using an ordinary Ziegler catalyst. The composition ratio of ethylene / propylene / ENB of the copolymer is 72/24/4 (weight ratio), and the Mooney viscosity is 105. (Referred to as TPE-2)
c) Copolymer of ethylene and octene-1 (TPE-3)
It was produced by a method using a metallocene catalyst described in JP-A-3-16388. The composition ratio of ethylene / octene-1 in the copolymer is 72/28 (weight ratio), and the Mooney viscosity is 100. (Referred to as TPE-3)

(C-1-2) Hydrogenated rubber a) Hydrogenated butadiene polymer The hydrogenated butadiene polymer is produced by hydrogenating a butadiene polymer based on the method described in WO 01/48079. The Mooney viscosity is 100. (Referred to as H-BR)
b) Hydrogenated styrene / butadiene copolymer Manufactured by hydrogenating a styrene / butadiene copolymer based on the method described in WO 01/48079. The styrene / butadiene composition ratio of the precursor copolymer is 70/30 (weight ratio), and the Mooney viscosity is 100. (Referred to as H-SBR)

(C-2) Olefin resin (C-2-1) Polypropylene Isotactic homopolypropylene (referred to as PP) MFR: 0.5 g / 10 min (230 ° C., 2.16 kg load)

(D) Crosslinking agent (D-1) Crosslinking initiator 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane (referred to as POX)
(D-2) Polyfunctional monomer Triallyl isocyanurate (referred to as TAIC)

[Examples 1-6 and Comparative Examples 1-11]
A twin screw extruder (cylinder inner diameter (D) = 40, screw length (L) (L / D) = 50) is used as the extruder.
The composition shown in Table 1 is melt-extruded at a cylinder temperature of 160 ° C. and pelletized. An injection molded article is produced from the composition thus obtained at 200 ° C. using an injection molding machine. The results are shown in Table 1.
According to Table 1, when the requirements of the present application are satisfied, it can be seen that the expansion ratio is extremely large.

  The foam obtained by using the foaming agent of the present invention includes automotive parts, automotive interior materials, airbag covers, mechanical parts, cables, hoses, belts, toys, sundries, daily necessities, building materials, sheets, It can be used in a wide range of applications, including film, and plays a major role in industry.

Claims (8)

  In a foaming agent comprising a microcapsule (A) having an average particle diameter of 1 to 1000 μm and a chemical foaming agent (B) enclosing a low boiling point liquid, foaming of the microcapsule (A) and the chemical foaming agent (B) A foaming agent having a starting temperature of 100 ° C to 200 ° C and a maximum foaming temperature of 150 to 250 ° C.   A foamable polymer composition comprising the foaming agent according to claim 1 and a polymer (C).   The polymer (C) is a crosslinked thermoplastic crosslinked rubber composition comprising a crosslinkable rubber-like polymer (C-1) and a thermoplastic resin (C-2). Foamable polymer composition.   Ethylene / α-olefin copolymer (C-1-1) produced using a metallocene catalyst, wherein the crosslinkable rubber-like polymer (C-1) contains ethylene and an α-olefin having 3 to 20 carbon atoms. Or hydrogenated rubber in which 50% or more of all olefinic double bonds of unsaturated rubber comprising a homopolymer and / or copolymer having double bonds in the main chain and side chain are hydrogenated (C-1 The foamable polymer composition according to claim 3, wherein the foamable polymer composition is one or more crosslinkable rubber-like polymers selected from the group (2).   The foamable polymer composition according to claim 3 or 4, wherein the thermoplastic resin (C-2) is an olefin resin.   The foamable polymer composition according to any one of claims 3 to 5, which is crosslinked with a crosslinking agent (D).   The composition further comprises at least one additive (E) selected from the group consisting of a softener, a powdery compound that does not melt at 250 ° C, a styrene thermoplastic elastomer, and a resin wax. A foamable polymer composition according to claim 1.   A foam obtained by molding the foamable polymer composition according to any one of claims 2 to 7 by an injection molding method, an extrusion molding method or a blow molding method.